The instant process is directed to an adsorption method for producing ultra low sulfur hydrocarbon streams, specifically naphthas while preserving octane.
Due to environmental regulations the amount of sulfur present in naphtha streams must be closely controlled. The regulations will require the amount of sulfur in gasolines to be reduced to about 150 ppm by the year 2000, with further reduction to about 30 ppm by the year 2004. Thus, there is a critical need for technologies that are capable of lowering the amount of sulfur present in naphtha streams.
Present technology for lowering the amount of sulfur in naphtha streams is accompanied by an octane loss since the technology saturates the olefins present in the streams. Thus, following the sulfur removal, the streams must be isomerized to regain octane. Such processes include the Mobil-Oct Gain and UOP/Intevap ISAL processes. However, these processes have substantial yield losses and are prohibitively expensive.
The instant invention is directed to a method for reducing the amount of sulfur in hydrocarbon streams comprising the steps of:
(a) contacting a hydrocarbon stream comprising hydrocarbons and sulfur compounds with an adsorbent selective for adsorption of said sulfur compounds, under adsorption conditions capable of retaining said sulfur compounds on said adsorbent and obtaining an adsorption effluent comprising a desulfurized hydrocarbon stream,
(b) collecting said desulfurized hydrocarbon stream,
(c) desorbing said sulfur compounds from said adsorbent by passing a desorbent through said adsorbent under desorption conditions to obtain a desorption effluent comprising sulfur compounds and said desorbent,
(d) treating said desorption effluent to remove said sulfur compounds from said desorption effluent and collecting a desulfurized desorbent effluent comprising desorbent.
The process may likewise comprises step (e) recycling said desulfurized desorbent effluent of said step (d) to said step (c).
The process may alternatively comprise combining said desulfurized desorbent effluent of said step (d) with said desulfurized hydrocarbon stream of said step (b) in a mogas pool.